单项选择题 Vingo sat there, never ______, his dusty face ______ his age. A．moving; masked B．moved; masked C．moving; masking D．moved; to be masked

单项选择题 有主管人生长发育和生殖功能的脏是( ) A．心 B．肺 C．脾 D．肝 E．肾

单项选择题 能起到治疗作用的氧浓度不能低于( ) A．21% B．30% C．25% D．35% E．45%